Multi-layer crossed bottom valve bags



United States Patent '0 F MULTI-LAYER CROSSED BOTTOM VALVE BAGS Carl Honsel, Herforderstrasse 285, Bielefeld, Germany Filed July 31, 1957, Ser. No. 675,365

Claims priority, application Germany Aug. 9, 1956 2 Claims. (Cl. 22962.5)

The present invention relates to crossed bottom valve bags, of the type made of a plurality of layers of material in flattened tube form. More in particular, the invention relates to bags of this type where the bottoms present a triangular area after the flaps are folded over and where means must be provided to avoid dust leakage between the edges of the flaps and said triangular area.

In multi-layer crossed bottom valve bags increasingly great emphasis is placed on having the crossed bottom closures absolutely leak proof against dust. In the conventional crossed bottom valve bags the danger of dust leaking of pul-verulent filler material takes place particularly at the ends of the edges of the bottom folds. In order to avoid this danger the closed, crossed bottom is frequently provided with a special closure patch. This closure patch is also known to be provided with a longitudinal fold at the outer edge of the flattened cross bottom, which extends over the wall of the bottom of the bag and for this form of closure the closure patch is of such length that a projecting triangular tip results at the edge of the longitudinal fold which is glued onto itself. In producing such cross bottom bags by machine methods it is difficult, however if a closure patch is used, to provide both bottom fold edges with a longitudinal fold which extends over both walls of the bag so that with this type of known crossed bottom, if made by machine, no triangular tips exist which are glued onto themselves at the bottom fold edges.

In multi-layer cross bottom valve bags it is furthermore known to provide the outer tube section or sections with incisions which permit the folding onto one another of the individual crossed bottom flaps. The incisions are then within the area of the edges of the bottom folds; i.e. they engage the fold edges or their ends (which correspond to the point of intersection of the bottom fold edges with the side edges of the triangular bottom pockets). Such multi-layer cross bottom valve bags can also be provided with a closure patch which has a longitudinal fold which lies against the corresponding wall of the bag at one of the bottom fold edges, so that also here the projecting triangular tips which are glued onto themselves, are obtained on one bottom fold edge. However, the danger of dust leakage at the end of the second bottom fold edge is still not eliminated.

A dust leak-proof closure at all ends of the bottom fold of such crossed bottom valve bags has thus far been possible only where a closure patch is applied manually which has a longitudinal fold at both bottom fold edges and is of such length that projecting triangular tips glued onto themselves are formed at all ends of the bottom fold edges.

It is thus an object of the invention to provide a multilayer crossed bottom valve bag having incisions permitting the folding into one another of the individual layers of the crossed bottom flaps which can be produced by machine and where a closure patch is not needed but where nevertheless all ends of the bottom fold edges can be closed to be dust proof by machine production methods alone.

2,962,204 Patented Nov. 29, 1360 'ice This object is achieved in that the incisions in the outer layer or layers of the multilayer crossed bottom valve bag are disposed outside the edge of bottom fold, cutting the projected line of the bottom fold and extending to the lateral edge of the bottom triangle pockets. As a consequence, projecting triangular tips which are glued onto themselves result at the ends of the bottom fold edge of the closed crossed bottom. A considerable advantage of this arrangement in accordance with the invention is that the solution of the problem which has been attempted frequently but never completely attained is now provided without any additional paper consumption and that, in fact, the closure patch having a longitudinal fold which was required heretofore is completely saved and that due to the elimination of the patch the mechanical production of the crossed bottom valve bag in accordance with the invention is greatly simplified.

The invention is of particular significance for stacked multi-layer crossed bottom valve bags as the dust proof closure of the crossed bottoms is especially difficult with this type of bag.

The objects and advantages of the invention will become more apparent from the following description and with reference to the accompanyingdrawings which illustrate the different stages-of production of the bags at the valve end and in which:

Fig. 1 shows the end of a multi-layer tube section illus trating the first step of the method in accordance with the invention;

Fig. 1a illustrates the corresponding step of the method illustrated in Fig. 1 as known heretofore;

Fig. 2 showsthe turned over crossed-bottom of the tube section on the valve end of the section wherethe valve is located in the conventional manner inthe triangular pocket formed in accordance with the invention; i

Fig. 2a shows the same phase of the manufacture as Fig. 2, as known heretofore;

Fig. 3 shows the partly folded bottom of the bag in accordance with Fig. 2;

Fig. 3a shows the same phase as Fig. 3 on the bag made according to the method known heretofore;

Fig. 4 is a section along line IV-IV of Fig. 3;

Fig. 5 shows the completed inner crossed bottom made by the method in accordance with the invention;

Fig. 5a shows the same view as Fig. 5 of the crossed bottom, but made by the method in accordance with the prior art;

Fig. 6 is a section taken along line VIVI of Fig. 5;

Fig. 7 shows the cross bottom as shown in Figs. 5 and 6 with one outer layer portion in final position;

Fig. 7a shows the similar view as Fig. 7 on a bag made by the method known heretofore;

Fig. 8 shows the completely closed crossed bottom of a bag made in accordance with the invention; and

Fig. 8a shows the completely closed crossed bottom of a bag made in accordance with the method of the prior art.

In the drawing the gummed areas of the flaps are rendered in stippled form.

The multi-layer tube section 1 is provided with the incisions 2 and 3 generally known per se. However, the incisions 3, contrary to the known incisions 2 do not extend inside the edges of the bottom folds 4a and 4b but they cut the projected lines thereof outwardly of and away from these edges, and also the incisions 3 are longer than the known incisions 2.

The crossed bottom is then turned up on the crossed bottom folding machine as illustrated in Fig. 2. It is seen that the edges of the corners 3a formed by the incisions 3 in the outer layer of the tube section 1 are located outside the bottom fold edges 4a and 4b shown in dotted lines while the corners 2a of the outer layer of the tube section 1 formed by incisions 2 are disposed in the usual manner within the bottom fold edges 4a and 4b. From this it results that the flap 5a formed in the bottom triangle pocket I of the outer layer is narrower than the width of the completed crossed bottom while the flap 5b of the bottom triangle pocket II is wider in the conventional manner than the width of the finished crossed bottom which is determined by the distance of the two fold edges 4a and 4b.

Fig. 3 shows the inner layers 6 of one bottom flap folded over while the outer layer 611 of the flap is not yet folded. In Fig. 5 the inner bottom flaps 6 and 7 are folded over while outer flaps 6a and 7a are not yet folded.

The fold locations of the crossed bottom closure in accordance with Fig. 3, 5 is further explained by the sectional views taken along lines IV-IV and VIVI as seen in Figs. 4 and 6. Fig. 7 illustrates the stage in which both inner layers 6 and 7 of the bottom flaps are closed while the outer layer 6a is in closure position while outer layer 7a is still unfolded. It is seen from Fig. 7 that from closing the outer layer 6:: a triangular tip 8a is formed at bottom flap 6 which is glued onto itself and.

which provides the dust leak proof closure or seal at the corner 9a of the bottom fold edge 4b while this glued triangular tip is clearly not provided on the valve side II of the bag.

The fully closed crossed bottom is shown in Fig. 8. The two outer layers 6a and 7a are folded over the inner flaps 6 and 7 in a manner thaton the side opposite the valve side II the glued triangular tips 811 and 8b have been formed over both ends of the fold edges 4a and 4b.

It is, of course, understood that prior to the individual folding operations glue is applied to the flaps in the usual manner, which results in a double glued crossed bottom.

Having now described my invention with reference to the embodiment illustrated I do not wish to be limited thereto but what I desire to protect by Letters Patent of the United States is set forth in the appended claims.

I claim:

1. A multi-layer crossed bottom valve bag having flap forming incisions in at least the outer layer and presenting transverse fold edges permitting folding of the flaps of the individual layers over one another, said incisions on at least one side of the bag extending across the projected lines of the crossed bottom fold edges outwardly of the ends of said fold edges and intermediate the ends of said fold edges and the longitudinal fold of said bag, and defining in the folded bag outwardly projecting triangular tips glued onto themselves endwise of the bottom fold edges and endwise of the edges of the inwardly folded flap of said outer layer.

2. A multi-layer crossed bottom valve bag having fiap forming incisions in at least the outer layer and presenting transverse fold edges permitting folding of the fiaps of the individual layers over one another, said incisions on at least one side of the bag extending across the projected lines of the crossed bottom fold edges outwardly of the ends of said fold edges and intermediate the ends of said fold edges and the longitudinal fold of said bag, and defining in the folded bag outwardly projecting triangular tips glued onto themselves endwise and outwardly of the bottom fold edges and endwise of the edges of the inwardly folded flap of said outer layer, said triangular tips having the base of the triangles thus formed extend along a fold line connecting said crossed bottom with the end of the outer longitudinal fold line and having one side defined by an outward extension of a bottom fold edge.

References Cited in the file of this patent UNITED STATES PATENTS 2,346,292 Co-ty Apr. 11, 1944 2,668,003 Jones Feb. 2, 1954 2,761,612 Grosset et a1 Sept. 4, 1956 2,830,750 Weeks et al Apr. 15, 1958 

